Bonhams Fine Jewellery sale in London on September 20 saw a unique item go under the hammer: a fancy intense blue diamond weighing 4.03-carats, which has been held in a private collection for nearly 30 years, sold for $3.6 million to Graff diamonds ($853,203 per carat).

According to Gem Konnect, the second highest value lot was a 9.61-carat Kashmir sapphire single-stone ring, which went for $1.14 million.